Step 4: Make the Bell
The pump is constantly filling the Grow Tub with water, but adding water slower than the drain can suck it out.
When the tub fills with water, it gets to the top of the standpipe, and starts to flow back into the Aquarium. When this happens, it sucks all of the air out of the space between the standpipe and the bell. The Bell over the standpipe maintains the siphon until the Grow Tub is empty of water.
To Make the Bell:
With the wood saw, make 8 cuts equally spaced on one end of the 2" pipe. The saw can make cuts on opposite sides of the pipe at the same time, so make one cut, then one 90deg from that, then cut each 'tooth' in half. (Too detailed?)
with the plier, grab a hold of a 'tooth' as close to the base as possible, and bend it back and forth until it snaps off. Do this to every other 'tooth' and you will be left with something that looks like the top of a castle turret. Use the file to smooth things out and make them pretty, if you'd like.
The purpose of these gaps is to let water flow into the Bell easily when the siphon starts. This will make sure that the Grow Bed drains quickly.